Fluidic memory element



1 Sept. 9, 1969 D, H, THORBURN l 3,455,777

FLUIDI C MEMORY ELEMENT Filed April 3, 1968 3,465,777 FLUIDIC MEMORY ELEMENT David H. Thorburn, Oak Park, Ill., assgnor, by mesne assignments, to Powers Regulator Company, Skokie, Ill., a corporation of Delaware Filed Apr. 3, 1968, Ser. No. 718,395 Int. Cl. F15c 3/ 06; F16k 11/10 U.S. Cl. 137--112 6 Claims ABSTRACT F THE DISCLOSURE The invention provides a bistable iiuidic memory element comprising a memory element body having an internal chamber, preferably cylindrical in shape. The chamber has control pressure inlet and outlet openings at longitudinally opposite ends and a magnetically conductive flow restricter, preferably spherical, longitudinally movable within the chamber. Magnets are located at opposite ends of the chamber, tending to retain the sphere adjacent to one or the other control pressure openings. A sensing pressure passage communicates with the chamber at the side, and is designed so that the sphere will restrict flow and provide a back pressure in the sensing pressure passage when the sphere is adjacent to one of the control pressure openings, but will provide substantially less back pressure when the sphere is adjacent to the opposite control pressure opening and does not restrict llow. The position of the sphere can thus be determined by passing a fluid through the sensing pressure opening and measuring the amount of pressure in the sensing pressure inlet passage. The device is adaptable for use with both liquids and gases.

The present invention relates to a bistable fluidic memory element. j

As used herein, the terms fluid and lluidic refer to either liquids or gases. A bistable memory or flipflop element of the type described herein has the ability to change its polarity upon the application of fluidic input signals, and to provide a fluidic signal indicating the state of polarity. Such a device provides olf-on or yes-no signals responsive to the direction of a iiuidic flow or pulse. This has many applications in fluidic control systems, as well as in fluidic computers.

Generally, the present invention relates to a bistable iluidic memory element wherein the memory element body has an internal chamber with which a pair of control pressure passages communicate at opposite ends. A magnetically conductive flow restricter is located within the chamber, and is movable between the opposite ends. Magnets are positioned to create magnetic fields which tend to retain the flow restricter adjacent to one or the other control pressure opening. The iiow restricter can be moved from a position adjacent to a given control pressure opening to a position adjacent to the opposite control pressure opening by a flow or pulse of fluid from one of the control pressure openings. In order to permit discovery of the position of the flow restricter, the invention includes sensing pressure inlet and outlet passages in the memory element body communicating with the chamber at sensing pressure inlet and outlet openings which are positioned so that the flow restricter restricts the passage of fluid between them when it is retained adjacent to one control pressure opening by one of the magnets, but does not restrict the passage of fluid when it is retained by the other magnet. The sensing pressure inlet passage of course has a constriction and communicates with pressure sensing means at a point downstream from the constriction to detect the position of the llow restricter.

United States Patent O ICC The invention, both as to its organization and method of operation, together with the objects and advantages thereof, will be best appreciated by reference to the following detailed description taken in conjunction with the drawings in which:

FIGURE 1 is a partially cross-sectional side elevation view of a preferred embodiment of the present invention in one of two possible stable positions;

FIGURE 2 is a partially cross-sectional side elevation similar to FIGURE l, but showing the device in the other stable position; and

FIGURE 3 is a partially cross-sectional view taken along line 3 3 of FIGURE 1.

Referring to FIGURE 1, a preferred embodiment of the present invention comprises a bistable lluidic memory element generally indicated by reference numeral 10. The memory element 10 basically comprises a memory element body 12 having a generally cylindrical internal chamber 14. For reasons that will become apparent, the axial length of the chamber 14 must be greater than its diameter. A rst control pressure passage 16 and a second control pressure passage 18 communicate with the chamber 14 at iirst and second control pressure openings 20, 22, respectively, at axially opposite ends.

A flow restricting sphere 24 of magnetically conductive material such as steel is positioned Within the internal chamber 14. The diameter of the sphere 24 is preferably slightly less than the inside diameter of the chamber 14, so that the sphere 24 is in close spaced relationship with the chamber wall. As can be seen in FIGURE l, the sphere 24 is movable within the chamber 14 along the axis. This is the reason that the cylindrical chamber 14 must have an axial length greater than its diameter since if this were not true a sphere in close spaced relationship with the side Walls would not be axially movable. It will of course be appreciated that it is not essential to utilize a spherical flow restricter and cylindrical chamber in the present invention, so long as the iiow restricter is movable within the chamber responsive to pressure changes in the first and second control pressure passages. However, the combination of a spherical ilow restricter and cylindrical chamber is clearly preferred.

A sensing pressure inlet passage 26 communicates with the internal chamber 14 at a sensing pressure inlet open, ing 28. vOpposite the sensing pressure inlet opening 28, a sensing pressure outlet passage 30 communicates with the chamber 14 at a sensing pressure outlet opening 32. As shown in FIGURES l and 2, the sensing pressure inlet and outlet openings 28, 32, respectively, are preferably aligned on opposite sides of the cylindrical chamber 14. However, such an orientation is not essential to the operation of the present invention, as will be understood by those skilled in the art. In the most preferred embodiment, the sensing pressure inlet opening 28 forms a seat for the flow restricting sphere 24, as shown in FIGURE 2.

A iirst magnet 34, preferably of the permanent type, is located below the cylindrical chamber 14 and adjacent to the first control pressure opening 20. Similarly, a second magnet 36 is located adjacent to the second control pressure opening 22. The magnets 34, 36 are designed and positioned to create a magnetic lield tending to retain the sphere 24 adjacent to their adjacent control pressure openings 20, 22. Thus, in the most preferred embodiment of applicants invention, the magnets 34, 36 each have a fmsto-conical top section adjacent to the internal charnber 14 in order to concentrate magnetic flux density to maintain the sphere 24 adjacent to one or the other control pressure opening. The second magnet 36 also most preferably is located within the sensing pressure inlet passage 26 close to the sensing pressure inlet opening 28. Since it is necessary that fluid be able to pass through the sensing pressure inlet passage 26 into the chamber 14, the second magnet 36 must include fluid channels. In the preferable design, Huid channels are formed between the second magnet 36 and the walls of the sensing pressure inlet passage 26. Thus, as shown in FIGURE 3, the second magnet 36 has a portion of generally square cross-section forming a base for the aforementioned frusto-conical portion. As can be seen in FIGURE 3, this base portion forms channels 38 between the second magnet 36 and the walls of the control pressureinlet passage 26.

Although not essential to the present invention, for simplicity of construction the first magnet 34 is identical to the second magnet 36. The first magnet 34 is located in a generally cylindrical receptacle 40, which may be closed by Va suitable plug 42.

Referring again to FIGURE 1, the sensing pressure inlet passage 26 has pressure sensing means 44 communicating therewith, for purposes of illustration shown as a simple pressure gauge. Of course, it will be understood that the pressure sensing means 44 will not generally be a simple pressure gauge as illustrated, but may include other stages of a logic or control system operating responsive to pressures within the sensing pressure inlet passage 26. The pressure sensing means 44 communicates with the sensing pressure inlet passage 26 through a pipe 46. Also shown in the drawings is a constriction 48 in the sensing pressure inlet passage 26. The constriction 48 causes a pressure drop across it when fluid is flowing, but causes little or no pressure drop when there is little or no fluid flow. In order to sense such a pressure drop, the pressure sensing means 44 communicates with the sensing pressure inlet passage 26 at a point downstream from Ithe constriction 48, i.e., between the constriction 48 and the chamber 14.

In operation, the bistable fluidic memory element of the present invention is adaptable for use with both liquid and gas systems, although the embodiment shown is particularly designed for use with a gas. Referring to FIG- URE 1, assume that a pulse of gas pressure has been delivered to the second control pressure passage 18. This will cause the sphere 24 to move to a position where it is retained adjacent to the first control pressure opening 20 by the first magnet 34. Gas is thus permitted to ow through 'the sensing pressure inlet passage 26, into the chamber 14 and exiting through the sensing pressure outlet passage 30. The constriction 48 causes a pressure drop, which is sensed as a relatively low pressure by the pressure sensing means 44. This could be interpreted, for example, as an off signal, a no signal, or zero in the binary system. This signal is delivered to other portions of a logic or control system as is well known in the art. Of course, a constant flow of gas through the sensing pressure inlet passage 26 is unnecessary. Since the sphere 24 will be retained in its position by the first magnet 34, its position can be learned at any time by simply passing a gas through the sensing pressure inlet passage 26 and sensing the pressure as soon as equilibrium is reached.

Referring to FIGURE 2, assume now that a pressure pulse has been delivered through the first control pressure passage 18 as indicated by the arrow in FIGURE 2. Of course, a similar result could be obtained by a continuous fluid pressure in the first control pressure passage 16 that is higher than that in the second control pressure passage 18. The sphere 24 moves from the position shown in FIGURE 1 to become seated in the sensing pressure inlet opening 28 where it is held by the second magnet 36. When gas is delivered through the sensing pressure inlet passage 26 as before, it will be unable to pass into the chamber 14 and to the outlet passage 30. The pressure therefore will not drop across the constriction 48, and the pressure sensing means 44 will thus indicate a relatively high pressure. This may be interpreted by other portions of the system as, for example, an on or yes signal, or as one in the binary system. Again, it is only necessary to intermittently deliver gas to the sensing pres- 4 sure inlet passage 26 when it is desired to determine the position of the sphere 24.

Since the position of the sphere within the cylindrical chamber 14 is influenced by the control pressures and maintained by the magnets 34, 36, an advantage of -the memory element 10 of the present invention is that it may be used in any orientation, since gravity has only a minor effect.

It will of course be understood that it is not essential that the sphere 24 be able to seat itself in the sensing pressure inlet opening 28. For example, a relatively high pressure in the sensing pressure inlet passage 26 is obtained any time the sphere 24 blocks the free passage of gas from the sensing pressure inlet passage 26. Thus, the sphere 24 could block the outlet passage 30 instead of the inlet passage 28 if fiuid were not free to exit through one of the control pressure passages 16, 18. Similarly, it will be seen that it is unnecessary for the sensing pressure inlet and outlet openings 28, 32, respectively, to be aligned. All that is required is that the flow of fluid from the 4.sensing pressure inlet passage 26 be restricted when the flow restricter 24 is retained by the second magnet 36.

Obviously, many modifications Iand variations of the present invention as hereinbefore set forth will occur to those skilled in the art, and it is intended to cover in the appended claims all such modifications and variations as fall within the true spirit and scope of the invention.

I claim:

1. A bistable fluidic memory element comprising: a memory element body having an internal chamber and first and second control pressure passages communicating with said chamber at first and second control pressure openings at longitudinally opposite ends thereof; a magnetically conductive flow restricter movable in said chamber between said opposite ends; a first magnet creating a magnetic field tending to retain said fiow restricter adjacent to said first control pressure opening; a second magnet creating a magnetic field tending to retain said flow restricter adjacent to said second control pressure opening; sensing pressure inlet and outlet passages in said body, said sensing pressure inlet passage having a constriction, and said sensing pressure passages communicating with said chamber at sensing pressure inlet and outlet openings positioned so that said ow restricting means restricts the passage of fluid between them when said flow restricting means is retained by said second magnet; pressure sensing means communicating with said sensing pressure inlet passage at a -point downstream from said constriction.

2. The memory element as defined in claim 1 wherein said chamber is substantially cylindrical and said ow restricter is a magnetically conductive sphere axially movable Within said chamber and in close spaced relationship with the Walls thereof.

3. The memory element as defined in claim 2 wherein said second magnet is located within said sensing pressure inlet passage adjacent to said sensing pressure inlet opening, and wherein said sensing pressure inlet opening forms a seat for said fiow restricter when said flow restricter is adjacent to said second control pressure opening.

4. The memory element as defined in claim 3 wherein said sensing pressure inlet and outlet openings are aligned with one another.

5. The bistable fluidic memory element comprising: a memory element body having an internal, substantially cylindrical chamber and said first and second control pressure passages communicating with said chamber at first and second control pressure openings at axially opposite ends thereof; a spherical, magnetically conductive flow restricter in said chamber, said flow restricter in close -spaced relationship with the side walls `of said chamber and axially movable therein; sensing pressure inlet and outlet passages in said body and communicating with said chamber at aligned, transversely opposite sensing pressure inlet and outlet openings, said sensing pressure inlet passage having a constriction, and said sensing pressure inlet opening forming a, seat for said flow restricter; a rst permanent magnet located adjacent to said tirst control pressure opening and creating a magnetic field tending to retain said sphere adjacent to said first control pressure opening; a second permanent magnet located in said sensing pressure inlet passage and terminating adjacent to said sensing pressure inlet opening, said second magnet shaped to form gas channels between said magnet and the walls of said sensing pressure inlet passage to permit the passage of gas through said sensing pressure inlet passage to said sensing pressure inlet opening, and said second magnet tending to retain said sphere seated in said sensing pressure inlet opening adjacent to said second control pressure opening; and pressure sensing means communicating with said sensing pressure inlet passage at a point downstream from said constriction.

6. The memory element as defined in claim 5 wherein said permanent magnets have frusto-conical tips converg- References Cited UNITED STATES PATENTS 3,422,259 1/1969 Freeman 23S- 201 WILLIAM F. ODEA, Primary Examiner W. H. WRIGHT, Assistant Examiner U.S. Cl. X.R. 

